Epoxy resins are widely used in many industrial applications. Epoxy resins have good thermal and chemical resistance, in addition to effective electrical and mechanical properties enabling their use, in particular, as an adhesive on a wide range of substrates. Epoxy resins are particularly useful in microelectronics. One such application is as a die-attach adhesive to bond a chip or die to a carrier or a circuit board. However, in some applications epoxy resins are generally too brittle, lacking the flexibility required, for example, to cope with thermal cycling. Flexibility can be imparted to an epoxy resin by incorporating an impact modifier. Suitable materials are described in U.S. Pat. No. 6,242,513-B (column 5, lines 35-62). Liquid synthetic rubbers such as functionalised polybutadiene copolymers are particularly preferred, especially in microelectronic applications. Unfortunately, the components of synthetic rubbers can be toxic, and it is preferred not to use these materials for environmental reasons. In addition, moisture uptake of an epoxy adhesive containing synthetic rubber can be a problem which can lead to thermal instability or “popcorning” of the completed electronic device. Such materials can also suffer from ionic contamination by alkali metal and chloride ions which can result in corrosion of the electrical components.